Means for providing an air curtain at an open doorway



27, 1966 E. BERNER' ETAL 3,294,%

MEANS FOR PROVIDING AN AIR CURTAIN AT AN OPEN DOORWAY Filed Feb. 23, 1965 9 2 Z A F f IV cold R l y D F 0.4.. Fl 65. g g

ErLing ernemChristlan United States Patent 3,294,006 MEANS FOR PRGVIDING AN AIR CURTAIN AT AN OPEN DOCRWAY Erling Berner and Christian Berner, New Castle, Pa., as-

signors to Berner Industries, Inc, New Castle, Pa, a

corporation of Pennsylvania Filed Feb. 23, 1965, Ser. No. 434,515

- 3 Claims. (CI. 98-36) This invention relates to means for providing an air curtain at an open doorway and one of the objects of the invention is to provide for increased efiiciency in the use of such a device.

It has been ascertained by tests in different laboratories in both England and the United States, that with one air curtain provided at an open doorway, the maximum reduction obtainable is around 80% of the heat loss that takes place without an air curtain and with the doorway open.

It has also been tested and proven that with two air curtains-one directing cold air downwardly at the cold side of the door opening and the other directing warm air down at the warm sidethe heat loss can be reduced still further. This difference is very important, as the heat loss for a doorway measuring 8x 8' is about 700,000 B.t.u. without air curtain for a temperature difference of 90 F., 70 F. on the warm side, and -20 F. on the cold side. With one air curtain that is perfectly balanced, the loss can be reduced to 140,000 B.t.u. With two air curtains, and with the circulation precisely balance'd, the loss can be brought down to 35,000 B.t.u. This reduction is very important, especially in cases where it is essential to bring the B.t.u. loss to a minimum.

The cost for two air-curtain-producing devices makes such an arrangement less desirable. It also is, in many cases, a matter of space which is not always obtainable on both sides of the doorway. Therefore, sometimes two air-curtain-producing devices combined in one unit are desirable, but inasmuch as two fans and two plenums are required, the costs are about the same as for two separate devices.

An object of this invention is to utilize only one fan but nevertheless have the advantage of two air curtains. By arranging an ejection suction with the air stream from the air curtain outlet, it has been proved possible to obtain two currents parallel to one another and thus secure the increased protection desired.

In earlier uses of suction to create a mixing of two different air streams, the purpose of ejection has been to obtain a suction and thereafter mix the ejected air or other gas with the ejecting air or gas. In the present invention the principal purpose is to suck in air or other gas of other physical properties, and direct such air or gas with a minimum of mixing, in the direction desired.

The above effect can be obtained by making the nozzle length, after the ejection takes place, short enough to avoid total mixing, but long enough to get a satisfactory suction. When suction is arranged from one side only of the ejection outlet, and when the nozzle length after the ejection is of the correct length, all or nearly all of the sucked-in air is transferred over to the opposite side of the curtain. This is a unique result, and it can be very useful in cases where odor and dust that contaminate air in a room are required to be removed.

When suction is arranged from both sides of the ejection outlet, and when the nozzle length after the ejection is of the correct length, most of the sucked-in air from each side will remain on its own side of the curtain. This is also unique since it would be expected that a complete mix of all three air streams would be obtained rather rapidly. In connection with air curtains this can be used for sucking contained warm air in the building Patented Dec. 27, 1966 ICC through the ejection nozzle and returning it adjacent to the floor of the doorway back into the building. In such a case, the unit will actually serve as a double air curtain. The air which is so sucked into the air stream can be pre-heated before entering the suction part of the air curtain nozzle. The preheating can be obtained with any kind of heating device. I

If an infra-red heater is used, it can be placed in the suction part whereby the heat from the infra-red unit will be used to almost The infra-red radiation, if the unit is correctly located, will heat the surface of the entrance floor at the doorway and the heat created by the infra-red unit will heat the air passing into the air curtain. The heating of the air can be increased by using part of the infra-red radiation to pre-heat a material of any type which the air has to pass. Such material can be a dark-colored metal or ceramic screen, which can be made adjustable in respect to the amount of heat from the infra-red unit it can absorb. Thereby the preheating of the air is regulatable and can be adapted to meet the circumstances. Another feature which is essential with the use of ejection in the nozzle'outlet is, that the mass of air finally leaving the nozzle from the air curtain can be increased from 10 to 50% depending upon how large the suction openings are and if the suction is arranged on only one or both sides.

With these and other objects to be hereinafter set forth in view, we have devised the arrangement of parts and steps to be described and more particularly pointed out in the claims appended hereto.

In the accompanying drawing, wherein an illustrative embodiment of the invention is disclosed,

FIG. 1 is a vertical sectional view through the upper portion of a doorway, showing the improved air curtain device applied thereto;

FIG. 2 is an elevational view of a part of the air curtain device;

FIG. 3 is a cross sectional view of the device showing the application of a heater;

FIG. 4 is a similar view, showing the heater in a different position;

FIG. 5 shows how undesired combustion gases might be removed by the use of an ejection nozzle, and

FIG. 6 shows how a recirculating air circuit is created, and

FIG. 7 shows how the air curtain with the heater is mounted on the warm side of the doorway.

Referring to the drawing, 1 indicates an open doorway and 2 indicates generally the air-curtain-producing unit which may be of the type disclosed in US. Patent No. 3,157,105, dated November 17, 1964. This unit consists of a housing section 3 which houses a motor and fan 3a driven thereby, and a cylindrical plenum 4 extending from the fan housing 3. The air blast directed from the fan passes through the plenum 4 and from an elongated, angularly directed nozzle 5 located at the bottom of the plenum and having a slot outlet opening 6 through which the air is directed downwardly to form the air curtain.

Surrounding the nozzle 4 is a supplemental nozzle in the form of a housing 7 which is open at its upper and lower ends, and has its side walls 9 spaced from the plenum nozzle 4 as shown in FIG. 1. The open upper end of the nozzle housing 7 and its spacing from the nozzle 4 provides for an air entrance 8 into the nozzle housing 7. This air entrance can be a slot located only at one side of the plenum nozzle 4 or at both sides thereof as desired. Through this slot or slots 9a the air that is ejected is sucked into the housing 7 and is later expelled mainly on both sides of the ejecting air or gas stream that emanates from the nozzle 4.

For one or both of the ejected air streams, an extra housing such as shown at can be attached, and in which the ejected air can be treated by pre-heating, humidifying or filtering before entering the nozzle housing 7. This extra housing 10 can be so designed that when equipped with an infra-red heater as shown at 11 the surface under the air curtain will be heated by infrared radiation, and the ejected air stream passes a screen 12 which is heated by the infra-red heater 11. Thus, the ejected air is heated before it enters the nozzle housing 7. By varying the size and position of the screen, the amount of heat provided to the ejected air and the amount of ejected air can be varied.

If an infra-red gas heater is used, the hot combustion gases are also ejected, that still giving a warmer air stream. With the heater placed as in FIG. 3, it will be well protected from wind gusts.

In cases where the heating costs are of small consequence, an infra-red heater can be applied immediately behind an air curtain as shown in FIG. 4. The air curtain protects the infra-red unit from outside winds and will also help to dispose of the combustion gases from the infra-red unit, if gas is used for heating. If infra-red gas heaters are used, and the combustion gases are undesired due to, for example, bad odors, high humidity, etc., such gases can be removed from the building by using an ejection nozzle 14 as shown in FIG. 5. Also smoke or fog hanging in the upper part of the doorway and/ or right inside, could be sucked into the nozzle and expelled from the building.

The ejection nozzle with slot openings 8 on both sides can be used in combination with an air curtain for protecting cold storage doors or the like as shown in U.S. Patent No. 3,157,105 heretofore mentioned. When such an air curtain is balanced to prevent the cold air in the low temperature room to leave, the direct contact between the warm and cold air sometimes, when the humidity in the warm air is too high, will create condensation and fogging in the doorway. By using such an arrangement as is shown in FIG. 6, a circulating air circuit is created. The air which is re-circulated will take up moisture from the warm ejecting air. The moisture will be removed to the low temperature room. The air exposed to the air in the low temperature room will, with this arrangement, not contain as much moisture as the warm ejecting air from the warm room. The result is less fogging and less risk of producing ice on the floor.

When arranging air suction as mentioned herein, the air in the immediate vicinity of the air curtain will be less disturbed. One reason for this is that the air in the outer parts of the air curtain stream, when suction is arranged on both sides of the nozzle, is much less than in the center. Another reason is that suction into the nozzle will serve to act in a manner to create a certain vacuum at the upper part of the air curtain and in such a way present an area on the side of the curtain which is much calmer than if no such suction was entering.

Another use of the described air curtain is desirable when the protection of doorways for comfort is required. The curtain is then placed on the inside of the building or on the warm side as shown in FIG. 7. Pre-heating of the air can be had with infra-red, steam coils, hot-water coils or electricity in the same manner as heretofore described. This extra-heated air will return to the warm room if a nozzle housing as mentioned above, with open slots on both sides of the air curtain nozzle is used. This pre-heating will bring the temperature of the air above the room temperature, which is essential if persons working in the room inside the doorway are to be comfortable. The arrangement just mentioned is shown in FIG. 7.

Having thus described embodiments of the invention, it is obvious that the same is not to be restricted thereto, but is broad enough to cover all structures coming within the scope of the annexed claims.

What we claim is:

1. An apparatus for producing an air curtain comprising, a plenum mounted adjacent to a doorway and having an elongated nozzle from which an air curtain is forced, a housing arranged around the nozzle, said housing consisting of a tubular element encircling the outlet end of the nozzle and with no intervening elements between it and the nozzle and spaced from the nozzle to provide unrestricted spacing between said housing and the nozzle, the housing being open at the top at a point above the outlet end of the nozzle to permit the entry of air from atmosphere into said spacing by the aspiration created by air forced through the nozzle, the housing extending beyond the outlet end of the nozzle.

2. An apparatus for producing an air curtain comprising, a plenum mounted adjacent to a doorway and having an elongated nozzle from which an air curtain is forced, a housing arranged around the nozzle, said housing consisting of a tubular element encircling the outlet end of the nozzle and spaced from the nozzle to provide spacing between said housing and the nozzle, the housing being open at the top at a point above the outlet end of the nozzle to permit the entry of air into said spacing by the aspiration created by air forced through the nozzle, the housing extending beyond the outlet end of the nozzle, a deflector located between the plenum and doorway, said deflector being located above the upper air-entrance end of the housing and above the outlet end of the nozzle, and heating means disposed between the housing and said deflector to thereby heat the aspiratedairx 3. An apparatus for producing an air curtain comprising, a plenum mounted adjacent to a doorway and having an elognated nozzle from which an air curtain is forced, a housing arranged around the nozzle and spaced from the same, the housing being open at the top and spaced thereat from the nozzle, the housing being open at the bottom whereby air can be sucked into the housing through the spacing between the nozzle and housing and can be ejected out of the open bottom of the housing at the sides of the air curtain flow from the nozzle, an infra-red heater arranged adjacent to the top of the housing for heating the air entering the housing at the top of the same, and a screen interposed between the heater and the floor of the doorway.

. References Cited by the Examiner UNITED STATES PATENTS 2,418,266 4/1947 Kurth 9840 3,023,688 3/1962 Kramer 98-36 3,094,851 6/1963 Beckworth 98-36 X 3,157,105 11/1964 Tamm 9836 ROBERT A. OLEARY, Primary Examiner. JOHN OCONNOR, Examiner.

r W. E. WAYNER, Assistant Examiner. 

1. AN APPARATUS FOR PRODUCING AN AIR CURTAIN COMPRISING, A PLENUM MOUNTED ADJACENT TO A DOORWAY AND HAVING AN ELONGATED NOZZLE FROM WHICH AN AIR CURTAIN IS FORCED, A HOUSING ARRANGED AROUND THE NOZZLE, SAID HOUSING CONSISTING OF A TUBULAR ELEMENT ENCIRCLING THE OUTLET END OF THE NOZZLE AND WITH NO INTERVENING LEMENTS BETWEEN IT AND THE NOZZLE AND SPACED FROM THE NOZZLE TO PROVIDE UNRESTRICTED SPACING BETWEEN SAID HOUSING AND THE NOZZLE, THE HOUSING BEING OPEN AT THE TOP AT A POINT ABOVE THE OUTLET END OF THE NOZZLE TO PERMIT THE ENTRY OF AIR FROM ATMOSPHERE INTO SAID SPACING BY THE ASPIRATION CREATED BY AIR FORCED THROUGH THE NOZZLE, THE HOUSING EXTENDING BEYOND THE OUTLET END OF THE NOZZLE. 